SAN BRUNO, CA - At least four people are dead, two dozen more hurt, some seriously, and dozens of homes were destroyed after a fireball blazed through South San Francisco Thursday evening.

Flames shot sky-high over the San Bruno neighborhood, about two miles west of the San Francisco International Airport when an initial blast ripped through the area around 6 p.m. Thursday.

A spokesperson for the city of San Bruno says they have 3 confirmed fatalities. San Bruno Fire Chief Dennis Haag said it would take fire crews until at least Friday afternoon to do a full search for more victims of the blaze.

53 homes destroyed were known destroyed in the blast and fire and another 120 were reported damaged, Kelly Huston of California Emergency Management said.

The fire spread over 10 acres Thursday night and was 50 percent contained by late Thursday as firefighters battled the flames into the night, California Emergency Management Agency spokesman Jay Alan said.

Initial reports established the cause of the explosion as a break in a PG&E 16- to 24-inch natural gas line.

Pacific Gas and Electric Co. officials said in an e-mailed statement that the ruptured gas line was theirs, although they cautioned that the cause of the blast has yet to be determined.

"Though a cause has yet to be determined, we know that a PG&E gas transmission line was ruptured," the company said in a statement. "If it is ultimately determined that we were responsible for the cause of the incident, we will take accountability."

The fire burned in a hillside area a few miles from San Francisco International Airport, sparking initial speculation the fire had been sparked by a plane crash.

The fifth was in good condition and was not being admitted to the hospital.

Five victims were also brought to the Mills Health Center in San Mateo with minor burns, a hospital spokeswoman said.

Four victims were transferred to the Saint Francis Memorial Hospital's Bothin Burn Center in San Francisco, according to a hospital spokeswoman.

Three of the patients were in critical condition and one is in stable condition.

"We're not expecting any more cases at this time," said Theresa Edison, the director of the hospital's emergency department. "We're capable of taking more patients; we're not at capacity."

Transfer of the patients to the burn center implies that their burns were serious enough to warrant the kind of treatment the center offers, Edison said. Saint Francisco houses the Bay Area's primary burn treatment center.

One of the patients in critical condition was taken to Seton Medical Center in Daly City before being transferred to St. Francis, Seton spokeswoman Beth Volz said.

She said two other people were taken to Seton with minor burns and were discharged. The medical center was not anticipating admission of any other victims from the fire and explosion tonight as of 9:55 p.m.

A person who answered the phone at Seton Medical Center said the hospital was on a triage alert as the injured were brought to the hospital.

Emergency shelters opened

The American Red Cross established an emergency shelter for evacuees at the Veterans Memorial Recreation Center, located at 251 City Park Way at Crystal Springs Road in San Bruno, according to spokeswoman Melanie Finke.

Finke said members of the Red Cross team told her about 100 people were already at the shelter as of 8:15 p.m.

Finke said an evacuation shelter was also established at the Bayhill Shopping Center at San Bruno and Cherry avenues by emergency officials and that some evacuees had opted to go there.

Finke said the Red Cross was in the process of bringing in cots, blankets, food and water to the Red Cross shelter. She said basic health services would be available, but that people in need of treatment have sought other medical care.

"It is difficult at this point to know how many people are truly affected," Finke said.

Investigators on scene

The California Public Utilities Commission had an investigator on the scene sifting through evidence and said they planned to continue gathering information for the next few days.

"Our thoughts are with the many families that have suffered losses, injuries, and displacement," commission director Paul Clanon said in a statement. "Our trained experts will get to the root cause of the explosion and fire."

The commission said it planned to work with local officials, federal agencies, and PG&E.